Process for the production of trioxane

Abstract

The present invention relates to a process for producing cyclic acetal comprising i) preparing a liquid reaction mixture comprising a) formaldehyde source, b) an aprotic compound and c) a catalyst; and ii) converting the formaldehyde source into cyclic acetals.

The invention claimed is: 
     
       1. A process for producing a cyclic acetal comprising:
 contacting a formaldehyde source with a liquid medium comprising a sulfur-containing organic compound and a catalyst, the catalyst comprising trifluoromethanesulfonic acid, perchloric acid, methanesulfonic acid, toluenesulfonic acid, sulfuric acid, or a solid acid ion-exchange materiel; and 
 at least partially converting the formaldehyde source into a cyclic acetal, wherein the cyclic acetal comprises trioxane. 
 
     
     
       2. A process according to  claim 1 , wherein the sulfur-containing organic compound has a boiling point of 140° C. or higher, determined at 1 bar. 
     
     
       3. A process according to  claim 1  wherein higher than 10% of the formaldehyde source is converted into one or more cyclic acetals during the reaction. 
     
     
       4. A process according to  claim 1  wherein the liquid medium comprises at least 20 wt.-%, of the sulfur-containing organic compound. 
     
     
       5. A process according to  claim 1 , wherein the sulfur-containing organic compound is selected from the group consisting of organic sulfoxides, organic sulfones, organic sulfonate esters, and mixtures thereof. 
     
     
       6. A process according to  claim 1  wherein the sulfur-containing organic compound is selected from the group consisting of cyclic or alicyclic organic sulfoxides, alicyclic or cyclic sulfones, and mixtures thereof. 
     
     
       7. A process according to  claim 1  wherein the sulfur-containing organic compound is represented by formula (I): 
       
         
           
           
               
               
           
         
         wherein 
         n is an integer ranging from 1 to 6, and 
         wherein the ring carbon atoms may optionally be substituted by one or more substituents, selected from C 1 -C 8 -alkyl which may be branched or unbranched or by the formula (II): 
       
       
         
           
           
               
               
           
         
         wherein R 1  and R 2  are independently selected from C 1 -C 8 -alkyl which may be branched or unbranched or by the formula (III): 
       
       
         
           
           
               
               
           
         
         wherein 
         n is an integer ranging from 1 to 6, and 
         wherein the ring carbon atoms may optionally be substituted by one or more substituents, selected from C 1 -C 8 -alkyl which may be branched or unbranched; or by the formula (IV): 
       
       
         
           
           
               
               
           
         
         wherein R 3  and R 4  are independently selected from C 1 -C 8 -alkyl which may be branched or unbranched. 
       
     
     
       8. A process according to  claim 1  wherein the sulfur-containing organic compound is sulfolane. 
     
     
       9. A process according to  claim 1  wherein the reaction produces trioxane and tetroxane. 
     
     
       10. A process according to  claim 1  wherein during the process a reaction mixture includes the formaldehyde source, the sulfur-containing organic compound, and the catalyst, and wherein the reaction mixture comprises the sulfur-containing organic compound in an amount ranging from about 25 wt.-% to about 90 wt.-%. 
     
     
       11. A process according to  claim 1 , wherein the catalyst comprises trifluoromethanesulfonic acid, perchloric acid, methanesulfonic acid, toluenesulfonic acid, or sulfuric acid. 
     
     
       12. A process according to  claim 1 , wherein the formaldehyde source has a water content of less than about 20 wt.-%. 
     
     
       13. A process according to  claim 1 , wherein the formaldehyde source comprises an aqueous formaldehyde solution. 
     
     
       14. A process according to  claim 13 , wherein the aqueous formaldehyde solution contains formaldehyde in an amount from about 60 wt. % to about 90 wt. %. 
     
     
       15. A process according to  claim 1 , further comprising the step of separating the cyclic acetal from the liquid medium by distillation. 
     
     
       16. A process according to  claim 1 , further comprising the step of manufacturing polyoxymethylene from the cyclic acetal. 
     
     
       17. A process according to  claim 1 , wherein the formaldehyde source comprises gaseous formaldehyde. 
     
     
       18. A process for producing cyclic acetal comprising
 i) preparing a liquid reaction mixture comprising
 a) a formaldehyde source, 
 b) an aprotic compound comprising a sulfur-containing organic compound and 
 c) a catalyst, the catalyst comprising trifluoromethanesulfonic acid, perchloric acid, methanesulfonic acid, toluenesulfonic acid, sulfuric acid, or a solid acid ion-exchangepaterial; and 
 
 ii) converting the formaldehyde source into cyclic acetals; 
 wherein the cyclic acetals comprise trioxane. 
 
     
     
       19. A process according to  claim 1 , wherein the catalyst comprises a solid acid ion-exchange material. 
     
     
       20. A process according to  claim 10 , wherein the reaction mixture includes the formaldehyde source in an amount from about 20 wt. % to about 70 wt. %, contains the aprotic compound in an amount from about 25 wt. % to about 75 wt. %, and contains water in an amount less than about 20 wt. %. 
     
     
       21. A process according to  claim 13 , wherein during the process a reaction mixture comprises the formaldehyde source, the sulfur containing organic compound, and the catalyst and wherein the reaction mixture contains water in an amount less than about 20 wt. %. 
     
     
       22. A process for producing a cyclic acetal comprising:
 contacting a formaldehyde source with a liquid medium comprising a sulfur-containing organic compound in the presence of a catalyst, the sulfur-containing organic compound comprising an organic sulfoxide, a sulfone, or mixtures thereof; and 
 at least partially converting the formaldehyde source into a cyclic acetal, wherein the cyclic acetal comprises trioxane. 
 
     
     
       23. A process as defined in  claim 22 , wherein the sulfur-containing organic compound comprises sulfolane.